This application is related to, and incorporates by reference herein in its entirety, the commonly owned U.S. patent application, entitled xe2x80x9cA Heat Sink With A Cutoutxe2x80x9d filed concurrently herewith by Darin P. Smedberg, now U.S. patent application Ser. No. 10/071,968.
The present invention relates generally to fiber optic cable handling and more particularly to routing fiber optic cables around a printed circuit board.
Fiber optic cables may be mounted on a printed circuit board using a fiber guide 16 (FIG. 1) that is normally affixed to a printed circuit board 19 using rivets 18. Instead of rivets, other fasteners such as adhesive tape, screws, snaps or standoff may be used. Affixing fiber guide 16 to printed circuit board 19 normally requires that the printed circuit board 19 have a number of holes through which rivets 18 pass. A cable tie 14 may be used to attach an optical cable 10 to fiber guide 16.
As is well known in the art, optical cable 10 of FIG. 1 normally contains one or more fibers 12.
A fiber guide in accordance with the invention is indirectly supported by a printed circuit board, instead of being mounted directly thereon. Depending on the embodiment, one or more fiber guides are attached to an item (such as a heatsink, or a clip for attaching the heatsink) that in turn is supported in the normal manner (either directly or indirectly) on the printed circuit board. The indirect support of a fiber guide in accordance with the invention more efficiently uses the space on a printed circuit board, than if the fiber guide was directly mounted on the printed circuit board (as discussed above in the background section). Specifically, indirect mounting of the type described herein eliminates the holes of the prior art required for riveting the fiber guide to the printed circuit board, and frees up the space on the printed circuit board equal to the footprint of the fiber guide, thereby to allow this space to be used for other components (such as integrated circuits).
In one embodiment, one or more fiber guides are integrally connected to and formed as extensions of a heatsink clip (such an extended clip is also called xe2x80x9cdual purpose clipxe2x80x9d), for example at the periphery. Such extension(s) of a heatsink clip (e.g. one at each of four corners of a rectangular clip) may be formed of a thermally insulated material (such as plastic), so as to keep a cable supported by the extension(s) from being heated up by conductive heat transfer from a heatsink during normal operation. The material of the extension(s) may be same as the material of which a heatsink clip is normally formed, depending on the implementation. Therefore, in one embodiment, a heatsink clip and one or more fiber guides (formed as extensions therefore) are formed of a common material, as a single piece, although in other embodiments, one or more fiber guides may be mounted directly on a heatsink. A dual purpose clip of the type described above simplifies the assembly of a printed circuit board, and also reduces the total number of parts that need to be assembled, as compared to fiber guides that are separately mounted on a heatsink (or even on a printed circuit board).
In one embodiment, a dual purpose clip of the type described above includes a frame, one or more fiber guides attached to the frame, and one or more fasteners also attached to the frame. The frame may have a shape that depends on the heatsink and/or the electronic component to be cooled, for example a rectangular shape. In one specification implementation, four fiber guides are integrally connected to the four corners of a rectangular frame, and four fasteners are integrally connected to the four sides of the rectangular frame. Any type of fiber guides and/or fasteners may be used in such an implementation, depending on the design of the electronic component and/or the heatsink. Examples of fasteners include a snap-on/clip-on feature, e.g. fastening hooks, a spring feature, or a screw. Also, depending on the embodiment, the fiber guides and/or the fasteners may be made detachable from the frame. Moreover, although a rectangular frame is used in some embodiments, the frame can have other shapes (such as oval, circular or triangular) in other embodiments.
A fiber guide that is used in one specific example has a curvature, although in another embodiment there is no curvature. When a curvature is present, the curvature may be less than the curvature allowed by a minimum bend radius (e.g. as defined in an industry standard or by widely accepted practice) of a fiber optic cable. In one specific example, each of four fiber guides has the shape of an arc of a circle wherein the circle has the minimum bend radius, and the center of the circle is offset from the center of the frame, along a diagonal of the frame. In one specific implementation, a fiber guide used in a combination clip of the type described above has a number of walls that either partially or completely enclose an annular space around the arc of the circle, so that a fiber optic cable can be held in the annular space without need for a cable tie as in the prior art (described above in the Background section).